Q. Why is rotational latency typically not considered in disk scheduling? How would you alter SSTF, SCAN and C-SCAN to comprise latency optimization?
Answer: Most disks don't export their rotational position information to the host. Even if they did and the time for this information to reach the scheduler would be subject to imprecision and the time consumed by the scheduler is variable therefore the rotational position information would become incorrect. Additional the disk requests are typically given in terms of logical block numbers as well as the mapping between logical blocks and physical locations is very complex.